Dan, Dan, Dan. Before beating the living daylights out of your colleague for possibly being a murderer—and for cheating on his wife with the girl you wish you were sleeping with—maybe make sure the evidence checks out. "Human blood" on a shirt he was wearing doesn't necessarily mean "the murder victim's blood." Thankfully, Stanley Tucci's visiting DCI Morton is around to throw some cold water on all the sauna-addled Fortitude dwellers.